Research on therapeutic community (TC) process is critically needed. While meta-analysis has supported the effectiveness of TCs, it has also shown that effect sizes are often modest (Pearson &Lipton, 1999). It is likely that a better understanding of TC process would allow TC clinicians to improve outcomes. However, research on TC process is a daunting task. TCs rely on the interactions between residents as the primary method of treatment. The fundamental TC process questions-how do residents maintain cooperation with each other, how do interactions give rise to a helping community, and how do interactions predict outcomes-cannot be answered through analysis of individual traits. Analysis must extend to thousands of interactions between residents. This study is based on a partnership between Ohio State University researchers and five Ohio corrections-based TCs. In an attempt to assure accountability and fidelity to standards of TC treatment (De Leon, 2000), the five Ohio TCs have recorded several hundred thousand incidents of helping behavior in agency databases. These records include givers and recipients as well as dates. They can therefore be analyzed as a social network, with individuals as nodes and helping behaviors as directed links. The analysis of the network will aim to understand the way in which residents maintain cooperation within the TCs, the relationship between network characteristics and outcomes, and the overall community structure that arises through resident interactions. An appealing aspect of studying the cooperative behavior of TC residents is that such behavior is amenable to clinical intervention. It is therefore expected that this study will result in concrete suggestions for the improvement of TC clinical outcomes. PUBLIC HEALTH RELEVANCE: Substance abuse is a major public health problem and the therapeutic community in which residents help each other in recovery is a major mode of treatment, particularly in the corrections system. This project is an analysis of the patterns of mutual aid between therapeutic community residents, and the way in which those patterns correlate with resident characteristics upon entrance as well as with treatment outcomes. This knowledge will allow therapeutic community clinicians to foster more clinically effective interactions between residents.